Very basic questions about using DCC.

[Sarah Winfield]

When I had my oval of track, no points, set up (apart from the locomotive's own problems), I could run it round fine.

If I then introduce one point but leave the point in the straight through position should I continue to have no problems? I guess it's all about the point!

If I then switch that point will I then get a short?

Sarah Winfield

 

[Greg Elmassian]

It of course depends on how the switch is wired electrically. There are all metal switches that would not work.

I believe you have LGB and the power in and out of all the rails is constant irregardless of the switch position. Internally the switch makes sure there are no shorts as things move around.

With this brand, you only get a short if you make one on purpose ha ha! When you connect the left rail to the right rail (what is called a reversing loop even if it does not look like a loop).

Greg

 

[Sarah Winfield]

Is one half of the switch say positive and the other half negative and that still applies which ever direction the point is set to?

When I say half I mean longitudinally.

Sarah Winfield

 

[dunnyrail]

Is one half of the switch say positive and the other half negative and that still applies which ever direction the point is set to?

When I say half I mean longitudinally.

Sarah Winfield

Using my outside and inside rail concept. The outside is say red, next rail is green. Wher the point has split you will then get Red, Green, Red and Green. The points metal bits by where the moving part takes care of that on that bit of rail. Where there are 4 rails there are Jumper Feeds that take care if that, if you have a disconnected point look underneath and follow where the wires go to help your understanding.

To the right you can see the screwed wires that feed the 4 rail ends.

 

[JimmyB]

Is one half of the switch say positive and the other half negative and that still applies which ever direction the point is set to?

When I say half I mean longitudinally.

Sarah Winfield

Sarah you need to lose the negative/positive power concept. AC current is not positive and negative, even though that term is used in household 230 volt electrics, the negative just means it is the same polarity as the earth. In DCC Dunny uses "red wire" "green wire" which is as good a method as any. On the standard LGB point the remains the same regardless of where the point is switched, this is because these are dead frogs, and not auto isolating but hard wired to the rail leading from the frog.

 

[Jon-P]

So I have a related question, as I'm starting off in the digital world. I have my starter oval, looking for more track. I've seen on another thread that some track is not suitable for digital operation, is that because of the way the points are connected as per the description above?

If so, how can you tell the difference between digital and non-digital compatible track, is the key thing to look for wiring as illustrated above?

Is all new LGB track digital compatible or is some analog and some digital?

 

[ntpntpntp]

Where have you read this J Jon-P ? Was it related to some small scale points (not G scale)? There is a concept of a "DCC friendly" point in the small scales (to do with how the rails are electrically bonded to prevent shorts with wheels and point blades), but nothing like that in our G scale world as far as I know - you should be able to use any point.

There is a concern regarding Peco G45 points and LGB locos with skates, where some folk have experienced shorts at the frog V which have blown the DCC decoder.

 

[Neil Robinson]

There is a concern regarding Peco G45 points and LGB locos with skates, where some folk have experienced shorts at the frog V which have blown the DCC decoder.

Just for the record this isn't restricted to Peco points and LGB skates.
Occasionally LGB R3 points may have the same problem as can MTH skates. Often with MTH it''s down to less than perfectly aligned skates.

 

[Greg Elmassian]

The "DCC friendly" is often a "live frog" issue, or a "power routing" issue, or an issue where skates can short out usually near the frog.

All 3 of these are issues that bear understanding.

I took the skates off all my rolling stock... solves one issue. The rest of the issues are uncommon in the G scale world, as most people are using LGB or Piko, or Aristo...

So Jon-P, basically anything you buy will be fine...

Greg

 

[PhilP]

You should not have a problem with points.. You may have a problem with your track layout. - The 'reverse loop' or 'balloon loop' (which is probably the easier way to understand the problem?

If your track is configured with a single-line section to a 'loop' of track, which rejoins the single-line, then you have a reverse loop, and a short circuit within your track layout.
This can be solved with either a DPDT switch, a relay (wired in the same way) which can be operated at a distance, or a 'reverse loop module' which does it all automagically!

<posting interrupted, so others have answered this>

 

[Jon-P]

Thanks guys, that is very helpful. Obviously I must have mis-interpreted comments on another thread.

The plans (in my minds' eye) for my garden layout do include at least one reverse loop, i suspect the final topology will be more complex. Is the reverse loop module a passive device or powered from the track? Presumably they switch the signal on one rail over onto the other?

 

[Gizzy]

Is the reverse loop module a passive device or powered from the track?

The module is powered from the track Jon. I have 2 of the LGB ones, although Massoth make a similar device.

All you need to do is feed 2 wires from your main track to the device, and another 2 to your isolated return loop. The device isn't weather proof, so I place mine off the ground in a suitable building or container....

 

[Zerogee]

Is the reverse loop module a passive device or powered from the track?

The module is powered from the track Jon. I have 2 of the LGB ones, although Massoth make a similar device.

All you need to do is feed 2 wires from your main track to the device, and another 2 to your isolated return loop. The device isn't weather proof, so I place mine off the ground in a suitable building or container....

The important thing about the reverse loop modules is that when used on a DCC layout, they are completely automatic and "seamless" in operation - they need no input from you as operator, they just do their job and remove all the problerms that reverse loops can otherwise cause. Trains simply run, going happily round the loop in either direction and without hesitation (or indeed repetition or deviation....).

Jon.

 

[Jon-P]

The important thing about the reverse loop modules is that when used on a DCC layout, they are completely automatic and "seamless" in operation - they need no input from you as operator, they just do their job and remove all the problerms that reverse loops can otherwise cause. Trains simply run, going happily round the loop in either direction and without hesitation (or indeed repetition or deviation....).

Just a minute there, that sounds just the ticket....

 

[FrenchChuffed]

You just have to follow the instructions and make sure the isolator sections for the module are long enough to accommodate your longest engine. Just a point …(well not a point an observation)

 

[Zerogee]

Just a minute there, that sounds just the ticket....

Watch out for the Clergymen without underwear......

Jon.

 

[FrenchChuffed]

You will have compleately lost our non uk friends with that one.

 

[Zerogee]

You will have compleately lost our non uk friends with that one.

I know......

Jon.

 

[Greg Elmassian]

So Sarah, I guess that your question about DCC is answered with the "clergymen without underwear" post?

 

[Zerogee]

So Sarah, I guess that your question about DCC is answered with the "clergymen without underwear" post?

I thought we'd pretty well answered the question between us, in the first few posts.....?
Maybe not.....

Jon.